The subject matter disclosed herein relates to a condenser for a power plant.
In combined cycle power plants, a gas turbine engine generates power from the heat generated by the combustion of fuel and air. The heat is then reused to generate additional power as a result of the generation of steam that is introduced into steam turbines. Steam turbine discharge is then condensed in a condenser. Generally, such a condenser includes a body through which steam turbine discharge flows over cooling members and in which condensation occurs.
Currently, many combined cycle power plants are operated and shut down in cycles to save fuel and energy costs during period of low power requirements, such as nights and weekends. As such, the combined cycle power plants need to go through start-up operations frequently in accordance with their respective schedules and, in some cases, in response to unexpected power requirements. Start-up operations are, however, inefficient and time consuming so it is typically a goal of power plant designers to shorten start-up times as much as possible.
As an example, some combined cycle power plants are now maintained with ready-start conditions during shut down times. Ready-start conditions refer to several power plant characteristics including, but not limited to, the ability of a combined cycle power plant condenser to cool steam turbine discharge during shut down times. Steam discharge during shutdown is often limited to a small amount used for sealing the steam turbine against air ingress while the condenser is under vacuum. With that said, the cooling members of the condenser are generally ill equipped to condense the reduced quantities of steam turbine discharge that is produced during the shut down times. Because the normal condenser coolant pump is generally sized for 33% to 100% full steam flow, the need to run a pump to pump coolant to the cooling members during the shut down times is costly and inefficient. Due to the sizing of the condenser cooling members (tube bank) for full cooling water flow, flow from a small pump, although thermodynamically sufficient for cooling the shutdown steam flow, will not distribute evenly within the tube bank. The uneven distribution means some shutdown steam will not be cooled leading to excess temperature and pressure in the condenser.